Traditional means to identify the physiological severity of arterial disease are hampered by the inability to identify atheroma extent and composition. New techniques that identify atheroma in vivo are being developed. However, accurate methodologies for atheroma characterization have met obstacles, in large part due to the heterogeneous nature of the disease process. Novel acoustic targeting and highlighting agents, such as liposomes, may overcome these problems. Liposomes are phospholipid vesicles enclosing an aqueous space. We have developed a unique methodology that by composition and process entraps microbubbles within the liposomes, which become echogenic. This formulation also allows modification for antibody conjugation and therapeutic drug incorporation. This proposal describes a series of protocols to optimize highlighting and enhancing characteristics of these formulations in vitro and in vivo. Robust quantitative methodologies will be utilized. We plan to investigate the potential of these formulations to aid highlight, characterize, and quantify the progression of atheroma. Our long term goals are to determine, quantitate, and characterize the stage, extent, and pathophysiologic development of atherosclerosis, allowing directed therapy to improve physiologic flow following clinical intervention.